Lesson 2.6 Macromolecules

Name Date Period

Key Terms

Control Indicator Macromolecule Monomer

Engage Proteins are one of the most important molecules in living systems. In this unit we will investigate several different molecules and their role in living systems. 1. Shown below are several different foods. On the right are different kinds of organic molecules. List the foods under the types of organic molecules you believe they contain. You may list the foods under more than one kind of organic molecule.

Organic Molecules

Blueberries and Apples Chocolate Candy Butter

Eggs French Fries Steak Cheese

Salmon Avocado Ice Cream Breads

Sugars (Glucose, Fructose, Sucrose) Starch Protein Fat

Explore I Important Macromolecules Your teacher will give a brief lecture on the important macromolecules; write the necessary information in the table below. Macromolecule Definition Monomer Example

Simple Sugar

Carbohydrate

Complex

Sugar

Protein

Lipid

Nucleic Acid

Explore II Experimental Controls (adapted from the Online Biology Book) Often scientists use a control to compare results in an experiment. The control is the group in which all conditions are kept the

same. This is different from the experimental group in which all conditions are kept the same except for the single condition being tested.

Suppose you wanted to learn how bacteria affect the growth of different varieties of soybean plants. Your hypothesis might state that the presence of certain bacteria will increase the growth rate of each plant variety. Bacteria are present on the roots of the experimental plants, but not the controls. All other conditions- including soil, light, water, and fertilizer- are held constant for both groups.

2. What is a control? 3. Describe the function of a control in an experiment. 4. You have always wondered which brand of hand sanitizer is the most effective for killing bacteria on your hands. You have

decided to perform an experiment to test three brands of hand sanitizer to determine which brand is the most effective. Describe a control for this experiment and explain what this control would demonstrate.

Explore III Positive and Negative Controls The molecules presented at the beginning of the lesson are so important that scientists have devised tests to determine if

these molecules are present in a sample. You will first learn to use the indicators listed below to determine if these molecules are present. You will then test several foods using these indicators to determine what molecules are in the food. Before you test your food items, you will first need to observe positive and negative controls. A positive control will demonstrate the color of the indicator when a certain macromolecule is present, whereas a negative control will demonstrate the color of the indicator when a certain macromolecule is not present. 1. The teacher will review the safety procedures for the lab. 2. Your instructor and/or student volunteers will conduct each experiment as each protocol defines. 3. Record data for your observations.

Benedict’s Solution Indicator Test for Sugar

Lugol’s Iodine Solution Indicator Test for Starch

Biuret Solution Indicator Test for Protein

Paper Bag Test for Fats

Procedure Positive Control for Sugar 1. Fill a small test tube half way with glucose solution. 2. Place 5 drops of Benedict’s Solution in the test tube. 3. Note the color of the solution. 4. Place the test tube in a water bath of boiling water. 5. Note the color of the solution. Clean the materials for the next trial. Negative Control for Sugar 1. Fill a small test tube half way with distilled water. 2. Place 5 drops of Benedict’s Solution in the test tube. 3. Note the color of the solution. 4. Place the test tube in a water bath of boiling water. 5. Note the color of the solution. Clean the materials for the next trial.

Procedure Positive Control for Starch 1. Fill a spot plate depression with starch solution. 2. Note the color of the solution. 3. Place 2 drops of Lugol’s Iodine Solution in the spot plate depression. 4. Note the color of the solution. Clean the materials for the next trial. Negative Control for Starch 1. Fill a spot plate depression with distilled water. 2. Note the color of the solution. 3. Place 2 drops of Lugol’s Iodine Solution in the spot plate depression. 4. Note the color of the solution. Clean the materials for the next trial.

Procedure Positive Control for Protein 1. Fill a spot plate depression with egg white solution. 2. Note the color of the solution. 3. Place 10 drops of Biuret Solution in the spot plate depression. 4. Note the color of the solution. Clean the materials for the next trial. Negative Control for Protein 1. Fill a spot plate depression with distilled water. 2. Note the color of the solution. 3. Place 10 drops of Biuret Solution in the spot plate depression. 4. Note the color of the solution. Clean the materials for the next trial.

Procedure Positive Control for Fat 1. Place a small amount of butter on the brown paper square. 2. Rub the butter in a circular motion on the paper. 3. Allow the paper to dry. 4. Hold the paper up to the light. 5. Note the color and appearance of the paper. Negative Control for Fat 1. Place a drop of distilled water on a square of brown paper. 2. Allow the paper to dry. 4. Hold the paper up to the light. 5. Note the color and appearance of the paper.

Observations Positive Control Negative Control

Observations Positive Control Negative Control

Observations Positive Control Negative Control

Observations Positive Control Negative Control

Explain I 5. The teacher will display these images. Identify what these tests are identifying based on the colors, and identify the indicators

used.

6. Several tests are performed on a potato chip. The results are shown below:

Indicator Result Lugol’s iodine Purple (dark)

Benedict’s Solution Blue Biuret Solution Blue

Paper Bag smear Clear What molecules are present in the potato chip? (select all that apply) a) Starches b) Proteins c) Sugars d) Lipids

7. Several tests are performed on a chunk of salami. The results are shown below: Indicator Result

Lugol’s iodine Brown/Yellow Benedict’s Solution Blue

Biuret Solution Purple Paper Bag smear Clear

What molecules are present in the salami? (select all that apply) a) Starches b) Proteins c) Sugars d) Lipids 8. Several tests are performed on skim milk. The results are shown below:

Indicator Result Lugol’s iodine Brown/Yellow

Benedict’s Solution Orange Biuret Solution Pink

Paper Bag smear Not Clear (No change) What molecules are present in the milk? (select all that apply) a) Starches b) Proteins c) Sugars d) Lipids 9. Lugol’s Iodine is an indicator used to identify the presence of… a) Starches b) Proteins c) Sugars d) Lipids 10. Benedict’s solution is an indicator used to identify the presence of… a) Starches b) Proteins c) Sugars d) Lipids 11. Biuret solution is an indicator used to identify the presence of… a) Starches b) Proteins c) Sugars d) Lipids